The invention relates to a device for generating an image on an image surface with Nxc3x97M image elements which can be illuminated individually, comprising a plurality of semiconductor radiation sources, each of which generates radiation with at least one color, an optical imaging means with a beam guidance, by means of which a plurality of image elements can be illuminated with each of the semiconductor radiation sources.
The devices known so far for generating an image with laser radiation sources operate on the basis of projection devices, i.e. a large distance is provided between the optical imaging means and the image surface and the plurality of radiation sources serves to illuminate an integral fraction of the N image elements of one row or M image elements of one column or the entire N image elements of one row or the entire M image elements of one column at one point of time and to transfer to the next plurality of image elements at the next point of time. The optical imaging means is preferably arranged such that it comprises the radiation of all the radiation sources and images this onto the image surface as a unit and from time to time switches the illumination of a first plurality of image elements further onto the next plurality of image elements.
Proceeding from these known solutions, the object underlying the invention is to create a device for generating an image, with which it is possible to generate an image on an image surface in as simple a manner as possible using radiation sources.
This object is accomplished in accordance with the invention, in a device for generating an image of the type specified at the outset, in that the image surface is divided into a plurality of continuous image surface sections, each comprising a two-dimensional ensemble of image elements, that an illumination unit is associated with each of the image surface sections and that each illumination unit has at least one semiconductor radiation source and an optical imaging means of its own which is associated with this illumination unit and images a radiation outlet onto the corresponding image surface section in a free beam propagation.
The advantage of the inventive solution is to be seen in the fact that the individual illumination units can be arranged and assembled in a simple manner at the required distance from the image surface since, on account of the free beam propagation between the illumination units and the corresponding image surface sections of the image surface, no beam-guiding elements whatsoever, such as, for example, light guides, are required between the illumination units and the image surface in order to guide the radiation to the individual image elements since this is accomplished by the optical imaging means associated with the illumination unit with a free beam propagation.
The advantage of the inventive solution is also to be seen in the fact that with it it is possible to design the beam guidance more simply since the radiation of an illumination unit is used merely to illuminate one of the image surface sections and thus the beam can be guided in a simple manner.
In particular, a beam guidance in the form of a beam deflection is simple to realize since the beam has to be moved only over the dimensions of an image surface section and does not, as in the state of the art, have to be moved over the entire extension of the image surface at least in one direction.
When the dimension of the image elements and the image surface remains the same and a maximum deflection angle can be realized with simple means, this solution allows the distance between image surface and optical imaging means to be configured to be so small that the entire device can be designed as a flat screen.
As a result of the inventive idea of creating individual illumination units with at least one radiation source and an optical imaging means expressly associated therewith a concept is available which allows a plurality of identical illumination units corresponding to the number of image surface sections to be produced and these to be combined with one another in order to illuminate the total number of image surface sections.
Furthermore, it is also possible with this solution to design the optical imaging means in a more simple manner than the optical imaging means known from the state of the art, with which it was necessary to image a radiation field with an appreciably large cross section, consisting of the plurality of radiations, and to deflect this in at least one direction over large dimensions.
In order to be able to produce inventive devices in a particularly efficient manner it is preferably provided for the illumination units to be of an identical design. This possibility allows the illumination units for inventive devices to be produced in large quantities, wherein even illumination units produced with faults do not increase the production costs significantly since these can be eliminated by way of test procedures prior to the assembly of the illumination units to form inventive devices.
In this respect, it is particularly favorable when the illumination units are identically constructed and identically controllable modules so that the control of the illumination units can also be brought about particularly advantageously.
A particularly favorable arrangement of the illumination units provides for these to be arranged in a surface extending approximately parallel to the image surface. Such an arrangement of the illumination units allows the positioning of the illumination units relative to one another to be automated during the assembly of an inventive device.
This arranging of the illumination units may be realized particularly advantageously when the illumination units are arranged on a support, with which an exact positioning of the illumination units relative to one another is possible.
The exact positioning of the illumination units may be realized particularly expediently when these are provided with identical holding members and are held by them in corresponding receiving means on the support.
With respect to the type and arrangement of the image surface sections, no further details have so far been given.
In principle, the image surface sections could have different sizes.
It is, however, particularly favorable when the image surface is constructed from groups of image surface sections of the same size, i.e. the entirety of the image surface sections has several groups of image surface sections and within each of the groups of image surface sections these have the same size.
However, it is not a precondition that the image surface sections within one group are located immediately next to one another but rather it is likewise conceivable to arrange the image surface sections from different groups so as to be interconnected to one another.
The provision of groups of the same image surface sections likewise allows for a simplification during the production of the illumination units since identical illumination units can be made available for each group of image surface sections.
It is, however, even more advantageous when all the image surface sections have an identical size so that identical illumination units can be used for the image surface.
With respect to the shape and size of the image surface sections, further details have likewise not been given so far. One advantageous embodiment, for example, provides for the image surface sections to have maximum extensions which are in the same order of magnitude in the two directions defining the image surface and extending transversely to one another. This means that the image surface sections are not intended to have any line-like shape but at the most a rectangular shape.
It is, however, particularly advantageous when the image surface sections have maximum extensions which are approximately of the same size in the two directions defining the image surface. This means that the image surface sections have a shape approximating a regular polygon or a square.
One particularly advantageous solution provides for the image surface sections to have approximately the shape of a square or of a hexagon.
The advantage of such shapes of the image surface sections is to be seen in the fact that proceeding from a center point of the image surface sections the maximum beam deflection in the two directions defining the image surface is approximately of the same size and thus the optical imaging means can be configured in a particularly simple manner and also the beam deflection can be selected to be correspondingly simple.
With respect to the arrangement of the image elements belonging to each image surface section it would, for example, be conceivable to overlap the image surface sections insofar as next but one image elements of the image surface belong to one respective image surface section whereas the image elements located therebetween belong to another image surface section.
This would, in particular, be possible, for example, for the overlapping at the edge of consecutive image surface sections.
The inventive solution may, however, be designed in a particularly simple manner when all the image elements of one image surface section are located immediately next to one another, i.e. each of the image surface sections is always formed by the ensemble of image elements which are located immediately next to one another and which is then adjoined directly by the ensemble belonging to the next image surface section but without the image surface sections thereby overlapping.
With respect to the realization of the beam deflection, no further details have been given in conjunction with the embodiments described thus far. It would, for example, be conceivable to bring about a beam deflection by the beam deflection taking place for all the illumination units by means of one single beam deflecting device. This means that, for example, one beam deflecting element acts on all the illumination units or is effective for all the illumination units, wherein a relative movement between semiconductor radiation source and/or at least one part of the optical imaging means as well as the image surface section is generated for all the illumination units at the same time.
Since, in the present case, a plurality of illumination units is used which are directly associated with one image surface section, such a beam deflecting device effective for all the illumination units would have to be realized in a manner adapted precisely to the illumination units from a mechanical and optical point of view.
One particularly advantageous embodiment therefore provides for each illumination unit to have its own beam deflecting device associated with it, i.e. for each illumination unit to have not only a semiconductor radiation source and an optical imaging means but also a beam deflecting device associated with it so that illumination units of this type can be produced as standardized units which are simple to construct mechanically and optically and which can be combined with one another to illuminate the plurality of image surface sections.
Such a beam deflecting device is preferably designed such that with it a relative movement of the radiation field exiting from each illumination unit in relation to the image elements of the image surface section can be generated.
For this purpose it is preferably provided for at least one optical component of the illumination unit, i.e. the semiconductor radiation source and/or the optical imaging means, to be movable relative to the image surface section.
One possibility for the movable arrangement of one of the optical components preferably consists in arranging the radiation outlet of the radiation field from the semiconductor radiation source so as to be movable relative to the image surface section.
Alternatively or in addition thereto, it is likewise possible to arrange at least one component of the optical imaging means so as to be movable relative to the image surface section.
No further details have so far been given concerning the design of the beam deflecting device itself. It would, for example, be conceivable to provide a conventional drive for the beam deflecting device. It is, however, particularly favorable when the beam deflecting device comprises at least one micromechanical drive.
In order to be able to predetermine the beam deflection in two directions defining an area it is preferably provided for the beam deflecting device to comprise two drives operative in directions extending transversely to one another.
The drives for generating the beam deflection may be designed in the most varied of ways.
One advantageous embodiment provides for the drive to be designed as a displacement drive.
The displacement drive is preferably designed such that it has a guide arm which extends transversely to the direction of displacement, at one end supports the optical component of the illumination unit to be displaced and at the other end is securely arranged.
The guide arm preferably has a length which amounts to a multiple of the displacement path to be passed through so that the movement of the optical component in the direction of displacement takes place approximately linearly.
Furthermore, it is preferably provided for the guide arm to be deflectable by means of an electric field in the case of the displacement drive.
The guide arm preferably defines an initial position, proceeding from which the arm can be deflected by means of an electric field.
In order to bring about a controllable movement of the optical component in the direction of displacement the arm is preferably designed as a spring-elastic element which defines an initial position and which counteracts an increasing deflection out of the initial position with an increasing restoring force so that the deflection proceeding from the initial position can also be adjusted by specifying the strength of the electric field.
Alternatively to providing a displacement drive it is preferably provided for the drive to be designed as a tilting drive, i.e. a tilting of the optical component, preferably a component of the optical imaging means, can be brought about about an axis of tilt by means of the drive.
Such a tilting drive is preferably designed such that it has two support elements tiltable relative to one another about an axis of tilt, wherein one of the support elements is arranged on a base and the other one of the support elements supports the component to be tilted.
The two support elements are preferably connected by an elastically deformable material web which defines the axis of tilt between the two support elements on account of its deformability.
In order to bring about a tilting of the two support elements relative to one another these can preferably be acted upon with a force by means of an electric field acting on them.
In the simplest case, the force can thereby be applied by a capacitor arrangement.
The elastically deformable web between the two support elements preferably functions such that it defines an initial position and proceeding from the initial position counteracts a tilting movement with a restoring force which becomes stronger with increasing tilting, this restoring force then having to be compensated by a force to be applied by the electric field in order to bring about a tilting movement through a defined angle of tilt.
With respect to the operation of the drives, in particular, the micromechanical drives the most varied of solution possibilities are conceivable. One advantageous solution provides for one of the micromechanical drives to be designed as a static, adjustable drive, i.e. as a drive, with which displacements through defined distances or tilting movements about defined angles can be realized, wherein the respective position can preferably be maintained by the drive over a certain period of time.
Another advantageous solution, at least for the movement in one direction, provides for the micromechnical drive to be designed as an oscillating drive, i.e. this drive is not operated such that it adheres to static conditions, i.e. displacements or tilting movements, but rather it oscillates constantly back and forth with a predeterminable frequency and a predeterminable amplitude. This solution has the advantage that with it a rapid movement in the respective direction with adequate precision can be generated in a simple manner.
In this respect, it is particularly favorable when the oscillating drive operates close to its resonance frequency since, in this case, it is possible to operate the oscillating drive with less power.
Alternatively or in addition to the aforesaid embodiments, one particularly favorable solution provides for each illumination unit to have a row of radiation outlets which the optical imaging means images at the same time onto a row of image elements of the image surface section.
Such an arrangement creates the possibility of increasing the number of image elements illuminated at the same time and thus of simplifying, for example, the devices for illuminating all the image elements of one image surface section.
It would be conceivable, for example, to design the number of radiation outlets to be equal to half the number of image elements of the row of image elements and, at the same time, to illuminate respective next but one image elements, wherein, in this case, only a displacement of the radiation field impinging on the image surface section by one image element would be necessary in the direction of the row. This would likewise create the possibility of providing in this direction a simple means for moving the radiation field from the one image element to the next image element and at the same time of realizing a movement transversely to the row over all the rows of the image surface section. In both cases, it would be conceivable to provide oscillating drives for this purpose.
A particularly favorable solution does, however, provide for the number of the radiation outlets of the row to correspond to the number of image elements in a direction of the corresponding image surface section parallel to the row and for the illumination of the image surface section to be brought about by means of a beam deflection in a direction transverse to the row.
This solution creates the possibility of realizing all the image elements of the image surface section by means of a beam deflection in only one direction, wherein the realization of the beam deflection can be realized in the most varied of ways, such as described, for example, in conjunction with the preceding embodiments.
In order to be able to arrange the respective illumination unit on a support in an expedient manner with this embodiment of the inventive device it is preferably provided for the extension of the row of radiation outlets in the direction of its longitudinal direction to be smaller than the extension of the corresponding row of image elements in this direction. As a result, each illumination unit can have a smaller extension in the direction of the row than the corresponding image surface section and thus it is possible to arrange all the illumination units in a space-saving manner on one support, the extension of which corresponds at the most to the extension of the image surface.
In order to be able to illuminate the individual image elements in color, it has proven to be particularly favorable when each illumination unit has three rows of radiation outlets.
In this respect, the illumination unit is preferably designed such that radiation of one of three colors superimposable to form white light exits from each of the rows of radiation outlets so that defined mixtures of color may be achieved by way of the controlled activation of the three rows.
In order to be able to preferably and expediently image the three rows onto the image surface section with an optical imaging means it is provided for each of the various rows of radiation outlets to be activatable separately with respect to time via a control. In this case, a mixing of the colors does not, on account of the inertia of the optical perception of the observer, result due to the temporal congruence of the occurrence of the three different colors at an image element but rather the illumination of an image element with three different colors takes place one after the other so quickly with respect to time that on account of the inertia of the eye of the observer a mixing of the colors results due to an xe2x80x9caveragingxe2x80x9d of the color perception.
In conjunction with the preceding explanations concerning the individual embodiments it would, in principle, have been possible to subject the light of a semiconductor radiation source in addition to modulations. However, it is particularly preferred in the case of the embodiments described thus far for at least one semiconductor radiation source to be associated with each radiation outlet and for the intensity modulation of this radiation outlet to be brought about by way of intensity modulation of the semiconductor radiation source.
Alternatively thereto, a further, advantageous inventive embodiment provides for the illumination unit to have at least one row of modulation elements which modulate radiation in transmission and the respective light outlet areas of which form the radiation outlets which the optical imaging means images together onto the image surface section. The idea of this solution thus provides for additional modulation elements which allow the light of a semiconductor radiation source to be used at the same time for illuminating several image elements in that a selective modulation of the intensity for the respective image element is brought about via the modulation elements provided in addition, wherein several modulation elements arranged in rows are preferably provided and their radiation outlets are imaged at the same time onto the image surface section by the optical imaging means so that the illumination of several image elements is brought about at the same time.
In this respect, it is particularly favorable when the illumination unit has a two-dimensional matrix of modulation elements which form a two-dimensional matrix of radiation outlets, wherein these radiation outlets are all imaged at the same time onto the image surface section by the optical imaging means.
In principle, it is not necessary for this purpose for the number of radiation outlets to correspond to the number of image elements of the image surface section. It is always possible to illuminate a partial number of the image elements of an image surface section at the same time by way of additional beam deflection and, subsequently, the next partial number for such a time until all the image elements of the image surface section have been illuminated. It is, however, particularly favorable when the number of modulation elements of the matrix corresponds to the number of image elements of the corresponding image surface section so that all the image elements of an image surface section can be illuminated at the same time.
In conjunction with the embodiment described thus far no details have been given as to how the illumination of the radiation outlets of the modulation elements is intended to take place. A particularly favorable solution provides for the modulation elements to have entry areas which the at least one semiconductor radiation source illuminates. This means that, in this case, one semiconductor radiation source is used for the purpose of illuminating the light entry areas of all the modulation elements of one illumination unit. It is, however, also conceivable to divide the modulation elements into partial numbers and allocate one semiconductor radiation source to each partial number.
A solution which is particularly inexpensive from a functional point of view provides for the at least one semiconductor radiation source to illuminate the light entry areas of all the modulation elements of one illumination unit, wherein this type of design of the inventive device is preferably based on a one-color illumination of the image elements.
If a colored illumination of the image elements is provided, it is preferably provided for several semiconductor radiation sources each supplying different colors to be used for each illumination unit.
In general, it applies for all the embodiments described thus far that, in the case of a colored illumination of the image elements, the illumination unit has at least three semiconductor radiation sources for the illumination of each radiation outlet, these sources generating radiation in three colors which can be superimposed to form white light.
This solution provides, for example, for the radiation of the three semiconductor radiation sources to be mixed prior to the respective radiation outlet.
Alternatively thereto, it is provided for three radiation outlets to be associated with each image element, wherein radiation in one of three colors which can be superimposed to form white light exits from each of the radiation outlets. In principle, it is possible to mix the colors each time by way of a simultaneous illumination of an image element.
However, it is also possible for the three semiconductor radiation sources each generating different colors to be activatable at different points of time, wherein the activation must take place in such short periods of time following one another that the eye of an observer averages the three consecutive, different colors and thus obtains an impression of a mixture of colors.
Within the scope of the preceding explanations concerning the semiconductor radiation sources, no further details have been given as to how these semiconductor radiation sources are intended to be designed. One advantageous possibility provides for the semiconductor radiation sources to be designed as semiconductor diodes, wherein the semiconductor diodes may, for example, be designed as superradiating semiconductor diodes.
One particularly advantageous variation of a semiconductor diode provides for this to be designed as a resonant LED.
Another advantageous design of the semiconductor radiation source provides for the semiconductor radiation source to be designed as a laser radiation source.
With respect to the design of the laser radiation source, no further details have been given in conjunction with the preceding embodiments. It has merely been defined that the laser radiation source is intended to be designed such that it generates at least laser radiation with one color. This means that simple dark/light contrast images could be generated. A particularly advantageous solution, in particular, for example, for use in advanced display or television technology provides for the laser radiation source to generate laser radiation with several colors. It is particularly favorable, in particular, in order to be able to produce all colors when the laser radiation source generates laser radiation with three colors which can be superimposed to form white, preferably red, green and blue.
In this respect, it is conceivable to design the laser radiation source such that it comprises, for example, for each of the laser radiations a source, preferably a semiconductor laser, which are seated close to one another.
The laser radiation from each of the semiconductor lasers can be imaged onto the image surface section either by one optical imaging means or by the optical imaging means provided for each of the respective sources.
Another advantageous solution provides for each laser radiation source generating laser radiation with several colors to have several sources generating the laser radiation with the different colors and for the different colors to be coupled into a light guide which leads to the optical imaging means. As a result of the amalgamation of the different colors in one light guide a simple geometrical configuration can be produced, with which the three colors can be imaged onto the image surface section together with one optical imaging means.
In this respect, it is conceivable, depending on the type of sources and the activation of the individual image elements, to design the illumination unit such that it illuminates each image element at the same time with the colors provided for it at the respective point of time or that it illuminates the individual colors of the image element at short intervals one after the other so that an averaging over the colors takes place by a human eye looking at such an image.
An image element within the meaning of the present invention is not to be understood, in particular, in the case of generation of a multicolored image as a single geometrical point, at which the three colors are superimposed. An image element within the meaning of the invention has an endless extension and can be designed in the case of three colors such that the three colors are superimposed either completely or partially or that the three colors are located next to one another and the entirety of the areas illuminated by the three colors defines this one image element.
With respect to the design of the laser radiation sources no further details have so far been given. One advantageous realization possibility, for example, provides for the laser radiation sources to comprise semiconductor lasers as sources for the laser radiation.
Semiconductor lasers of this type may, for example, be edge emitters or vertical emitters.
It is also conceivable within the scope of the invention for the generation of short-wave laser radiation to use a semiconductor laser with frequency doubling.